The reuse of old buildings for new libraries has gained currency within the Library and Information Science (LIS) profession and has informed sustainability initiatives. Adaptive reuse benefits the environment by conserving natural resources and minimizing the need for new materials. This chapter provides a review of some key documents on sustainability, green libraries and the recycling and conversion of buildings as libraries. Building reuse provides an opportunity for sustainable thinking in library planning. Sustainability and going green are already evident in library architecture and design and there is a need to encourage embracing greener practices and adaptive reuse. Sustainability and going green are growth areas for the future. Adaptive reuse and repurposing buildings that have outlived their original purposes for different uses or functions while at the same time retaining their historic features are viable alternatives to new buildings. Building reuse is occurring in developed countries while some developing countries are saddled with challenges slowing adoption of the trend.